Studies show that young girls are much more devastated by their first break up than boys are, generally speaking, so hopefully it's just something she'll struggle with but eventually get over. It's good that she's being treated for depression. It's most likely her family, friends and her doctor all know her feelings of suicide, but if you run into a mutual friend, you may want to mention that she said something about possibly hurting herself. But that's really all you can do. Hopefully you were honest with her not just about why you didn't want to be with her anymore, but honest about everything throughout your relationship. But even if you were a jerk to her, it's ultimately her responsibility to move on and survive this. It's possible she won't, but if you were as honest and as kind and respectful as you could have been, then there's not much more you can do.